Evaluation of the stability improvement in power generation of a concentration photovoltaic module with supercapacitors

The pointing accuracy of a tracking system in concentration photovoltaic (CPV) varies over a range of error values. Among the external disturbances that can degrade the accuracy of trackers include temperature changes, wind loading, low direct normal irradiation conditions and soiling of sensors, ultimately leading to unstable output power of a CPV system. A supercapacitor has a higher power density than that of battery, allowing the supercapacitor to provide more power over a short period of time. This study examines the feasibility of using supercapacitors to improve the stability of power generation in CPV systems. Supercapacitors are incorporated into the CPV module circuit. The equivalent circuit of a single solar cell with a supercapacitor is then constructed and simulated for determining the optimized capacitance of the supercapacitors. Simulation results indicate that a module circuit with 10F supercapacitor can significantly increase the stability of the output voltage waveform under the condition of a tracking error around 0.3°. Moreover, the output voltage decreases only around 4%, with the tracking error around 0.3°. Capacitance of the used supercapacitors, which should be adjusted based on various conditions, is an important design parameter that alters the efficiency and cost of a CPV system.